A nuclear reactor includes a plurality of pipes, pipe sockets and the like, in which cracks, especially in the vicinity of welds, may arise and in which, during repair, one end of the pipe may be released so as to form an open pipe end for fitting a suitable sealing sleeve thereon. In view of the radioactivity in a nuclear reactor, such a sealing sleeve must be capable of being operated at a large distance. The sealing joint according to the invention is especially designed to fulfil this requirement.